mIRC never sends messages for CTRL+B, either. Nor does it send scroll messages to the input textbox window, yet it seems to have overridden that behaviour nicely. Please read the entire thread before you make another post, because you are asking silly questions.
Right.. but mIRC interprets those messages for a purpose and places control codes into the box.
What possible reason is there for mIRC to intercept messages telling the MDI client to scroll? If something tells the MDI client to scroll then it is because that is what the software wants it to do. There's no reason for Khaled to block functionality in mIRC just to fix other peoples' buggy software.
Last post on this topic because you're clearly not understanding what we're trying to tell you.